Yes, it is routed out.
I didn't have a good way of routing this material, so what I did was make mine from two pieces of wood. The one side was the poplular board, the other side where the stock connector goes was 3/8" plywood. This way all I had to do was cut the shape of the stock and the hole out of the 3/8" piece. When that was done, I glued the 2 pieces together. I used some wood filler to fill any gaps and sanded the pieces until they were smooth together.
When I was putting the finish on my stock, I used a varnish with stain already in it - Dark walnut I believe. After each coat of varnish, I dusted it with flat black spray paint along the edges. I did this about 3 times and finished with a last coast of varnish. It really gave it an aged, weathered look and helped hide the seam between the 2 pcs, because you can't see the grain change due to the dark color.